1. Field of the Invention
The present invention relates to an operator cab for heavy construction equipment capable of preventing a sliding door from rocking or rattling due to a shock or vibration applied to the cab in a state that the sliding door slidably mounted on the cab is opened or closed, as well as improving the durability and shock absorbing performance of a locking device and a locking holder.
More particularly, the present invention relates to an operator cab for heavy construction equipment, in which a roller received in an engaging groove is supported by the roller holder installed on both ends of a guide rail supporting the roller of a sliding door when the door is fully opened or closed, thereby preventing a sliding door from rocking or rattling due to the shock or vibration applied to the operator cab, and in which a housing of a female locking striker is inserted into a door locking device to absorb the shock and noise generated in a locking process.
2. Description of the Prior Art
Generally, a common hydraulic excavator has been used for a civil engineering work or construction work in a vast area and includes an operator cab at an upper structure supported by a lower traveling structure and working apparatus such as a boom, a bucket, etc.
In narrow and limited working environments such as a downtown area, however, an engine room mounted on the rear portion of the upper structure, as well as the working apparatus (e.g., boom) mounted on a front portion thereof, collides against exterior objects while the upper structure swings in operation. In addition, the operator cab collides against the exterior in its opening/closing operation.
In order to solve the above problems, the hydraulic excavator with a small swing type of heavy construction equipment, as conventionally known for a small swing or short swing excavator, has been developed to reduce the radius of swing of the operator cab or the upper swing structure.
The door of the conventional excavator is generally installed on the external wall of the cab in such a way that it is slidably opened or closed along a predetermined small radius on the external wall and the external surface of the operator cab and the door thereof are outwardly covered or bent in an arc shape to sufficiently secure an internal space of the operator cab in view of the structure of the cab.
More specifically, as shown in FIGS. 1 to 3c, conventional operator cab of the excavator includes a door 3 slidably installed on an external wall 2a. 
The cap includes a plurality of rails 4, 5, and 6 provided on the external wall 2a, a plurality of rollers 7, 8, and 9 mounted on the door 3, each of the rollers 7, 8, and 9 always being in engagement with the respective rails 4, 5, and 6 to support the door 3 when the door is slid between a closed position, in which a doorway is closed, and a fully opened position, in which the doorway is open, and pairs of strikers, each of pairs of strikers including female strikers 10 and 12 and male strikers 11 and 13, one of the pair of strikers being mounted on the door 3 and the other being mounted on the external wall such that at least one pair of strikers are engaged with each other when the door is in its closed position and at least one pair of strikers are engaged with each other when the door is in its fully opened position.
At least one of the pairs of strikers is mounted in such a way that the strikers are engaged with each other at a front edge portion of the door when the door is fully opened, and at least the other of the pairs of strikers is mounted in such a way that the strikers are engaged with each other at a rear edge portion of the door when the door is fully opened (U.S. Pat. No. 5,577,795).
In particular, as shown in FIG. 3c, the central roller 9 of the door 3 consists of a rolling roller 9a which is rotated in an X-axis direction to support the load of the sliding door 3 when the door 3 is slid, and a guide roller 9b which is rotated in a Y-axis direction to prevent the sliding door 3 from being released from the central rail 6 when the sliding door 3 is slid.
In case the excavator is driven when the sliding door 3 is fully opened or closed, the sliding door 3 swings left and right or rattles up and down due to the shock or vibration applied to the cab. As a result, an operator does not concentrate upon his work to lower the operation efficiency and to cause a safety accident.
Taking the above problems into consideration, a plurality of male and female strikers 10, 11, 12, 13, 14, and 15 are provided on the sliding door 3 and the cab 2 and are engaged with each other, as shown in FIGS. 1 and 2, so as to prevent the sliding door 3 from rocking or rattling due to the vibration applied to the cab 2, when the excavator works in a state that the sliding door 3 is fully opened (see FIG. 3b) or is fully closed (see FIG. 3a).
As shown in FIG. 1, locking strikers 16 and 17 are respectively installed on the sliding door 3 and the cab 2, so as to lock the sliding door 3 in the opened position or closed position. In this instance, the locking striker 16 is installed at a position adjacent to a doorway 2b, while the locking striker 17 is installed at a position far away from the doorway 17.
According to the structure of the conventional operator cab for heavy construction equipment, since the plurality of male and female strikers 10, 11, 12, 13, 14, and 15 (see FIGS. 1 and 2) and the locking strikers 16 and 17 (see FIG. 1) which can maintain the sliding door 3 against the cab 2 in a fully opened state or in a fully closed state are outwardly exposed from the sliding door 3, the cab suffers from the sever noise due to the shock. In addition, because of the increased number of components, the cost is raised, and the assembling time and process are increased, thereby lowering the production efficiency and thus the price competitiveness thereof.
Also, the door locking device of the conventional cab for heavy construction equipment includes a pair of male and female locking strikers 18a and 18b. The male locking striker 18a is fixed to a sidewall member 2c in such a way that the head 22a of a loader 22 protrudes outwardly in a longitudinal direction of a lock holder 20. The female locking striker 18b has a fixing member 21 of which a locking stepped portion is radially expanded or contracted at the opening of the housing 19 when the loader 22 is inserted into and engaged with the housing 19.
Specifically, in case the sliding door 3 is locked, the head 22a of the loader 22 passes through the housing 19 and the fixing member 21, and collides against the bottom of the fixing member. In this instance, the locking stepped portion of the fixing member 21 is contracted to a size less than the diameter of the head at a rear position of the head 22a, so that the head 22a of the loader 22 is fixed and supported by the housing 19 and the fixing member 21.
By contrast, the locking stepped portion of the fixing member 21 is expanded to a size larger than the diameter of the head 22a, so that the head 22a of the loader 22 escapes from the housing 19 and the fixing member 21.
In this instance, the door locking holder 20 directly collides against the front end 19a of the housing 19 to form a surface contact, when the head 22a of the loader 22 comes in contact with the bottom of the fixing member 21.
As a result, the conventional door locking device has a drawback in that one side of the front end of the door locking holder is worn, so that the door locking holder suffers from the severe uneven wear, thereby reducing its durability.
Also, in case of locking the sliding door, the noise and the vibration are largely generated due to the shock generated when the head of the loader collides against the bottom of the fixing member. In particular, when the front end of the locking holder is unevenly worn, a clearance or gap happens at the attached portion between the housing and the locking holder, thereby destabilizing the locking state of the door and lowering the ability of absorbing the noise and vibration.